1. Field of the Invention
The invention relates to fault detecting circuits, and more specifically relates to a circuit for detecting faults or failures in a circuit board with a high level of competence. Even more particularly, the invention relates to a universal built-in-test (BIT) monitoring circuit using signature analysis.
2. Description of the Prior Art
Built-in-test (BIT) circuits are well known in the art. A BIT device is generally an electronic circuit, used in conjunction with a host computer or on-board processor, which will help fault isolate a digital circuit.
In many conventional BIT devices, the processor generally plays a major role in controlling the operation of the BIT device. The BIT device receives a relatively large amount of operation and control data from the processor, and is highly dependent on the processor to run its test procedure. There is, in effect, significant software involvement in carrying out a BIT operation.
Many conventional BIT devices are functionally limited. For example, in some applications, the BIT device is limited to testing whether the digital circuit is receiving data properly from the processor. The BIT device reads the data, and provides that same data back to the processor to verify that the data is being received properly. Such conventional BIT devices only test the receiver/transmitter interface portion of the digital circuit or the data bus between the digital circuit and the processor.
Most conventional BIT devices are designed to operate on only one specific digital circuit, and cannot be programmed to test a variety of digital circuits.